Qualification of Reactor Physics Toolset for a Thorium-Fuelled CANDU Reactor

AECL has developed enhanced versions of the reactor physics computer codes for analysis of CANDU^® reactors and the ACR-1000™. The central codes that comprise the analysis toolset are WIMS-AECL (a lattice code), RFSP (a core code) and MCNP5 (a Monte Carlo code). The toolset, with ENDF/B-VI nuclear data, has been validated for application to the ACR-1000 design. In addition to comparisons of code predictions against relevant experiments conducted in AECL’s ZED-2 critical facility, advanced methods based on cross-section sensitivity/uncertainty (S/U) analysis were used to extend the results of bias and uncertainty in reactivity coefficients, derived from analysis of ZED-2 tests, to the ACR-1000 reactor. The validation of this toolset with ENDF/B-VII nuclear data is proposed for application to analysis of a Thorium-fuelled CANDU Reactor (TCR). The TCR is based on the Enhanced CANDU 6™ (EC6™) reactor [1] and would operate with a fuel design that incorporates both low-enriched uranium (LEU) oxide and thorium oxide fuel elements in the same fuel bundle to achieve enhanced fuel and core performance with thorium fuel. For the initial TCR toolset qualification, important reactor physics phenomena would be validated using several relevant ZED-2 experiments performed in the past. Results from experiments with a variety of oxide fuels are available, including plutonium/thorium (Pu/Th), ²³³U/Th, ²³⁵U/Th, LEU and CANDU-MOX (containing a mixture of plutonium, uranium and dysprosium to simulate the reactor physics affects of fuel burnup). Taken together along with other relevant experimental data, these experiments would be expected to address the important isotopes and many phenomena for the TCR and to enable the validation of the reactor physics toolset for this design. Additional confirmatory experiments would reduce uncertainties. This paper describes the qualification process, including validation, which is proposed to support the use of the reactor physics toolset for the TCR.